EMLViewer

Minimalist .eml and .msg viewer for macOS. Double-click an email in Finder - the window opens, renders the message and gets out of your way. Built with Swift, SwiftUI, AppKit and WKWebView. Zero runtime dependencies.

Features

• Two formats in one binary
  • .eml (RFC 822 / MIME): full MIME tree, RFC 2047 encoded-words, quoted-printable, base64, charset decoding
  • .msg (Outlook Compound File Binary): CFB parser reads subject, sender, recipients, plain and HTML body, inline images and attachments via MAPI property streams
• Decoded headers: From, To, Cc, Subject, Date
• HTML rendering via WKWebView with inline cid: images resolved from MIME parts
• Plain-text fallback for messages without an HTML part
• Attachments bar with Finder-style file icons, click to open in the default app, Download All to ~/Downloads
• One-click Set as default for .eml and .msg: after that, double-clicking a message just opens the window, reads the file, shows it. No onboarding, no tray, no background daemon
• Light / Dark / System appearance, window size persisted across launches (SwiftData)
• emlcheck CLI companion for inspecting MIME trees from the terminal

Install

Homebrew

brew tap noma4i/emlviewer https://github.com/noma4i/emlviewer
brew install --cask emlviewer

Download

Grab the latest EMLViewer.app.zip from Releases.

Requirements

• macOS 14.0+ (Sonoma or later, required by SwiftData)
• Swift 5.9+
• Xcode 15+

Build

The .app is always built by Xcode (xcodebuild) and written to dist/.

make bundle      # dist/EMLViewer.app (release, ad-hoc signed)
make run         # debug build + launch
make install     # copy into /Applications

Xcode IDE

open EMLViewer.xcodeproj

Test

make test

License

MIT